Solid state electronic timepiece

ABSTRACT

An electronic timepiece having a liquid crystal display for displaying a time standard signal which is supplied thereto is provided. A light source for lighting the liquid crystal display is disposed proximate thereto. A time correcting circuit including manually operated switches is coupled to an electronic divider circuit which supplies the timing signal to the display to correct the displayed digits of time counted thereby. The time correcting circuit is provided with a safety switch which in a first position allows a correction switch to effect correction of a displayed digit and in a second position protects against inadvertent time correction and allows the lighting of the light source to make the digital display readable in the darkness.

O v United States Patent [191 [111 3,913,312

Numabe Oct. 21, 1975 SOLID STATE ELECTRONIC TIMEPIECE [75] Inventor: Hitomi Numabe, Suwa, Japan Primary Exammer- E dlth Slmmons jackinon Attorney, Agent, or Fzrm-Blum, Moscovitz, Friedman [73] Assignee: Kabushiki Kaisha Suwa Seikosha, & K l

Tokyo, Japan [22] Filed: Dec. 26, 1973 [57] ABSTRACT [21] Appl. No.: 427,941 An electronic timepiece having a liquid crystal display for displaying a time standard signal which is supplied thereto is provided. A light source for lighting the liq- [30] Forelgn Apphcatlon Prmntypata uid crystal display is disposed proximate thereto. A Dec. 25, 1972 Japan 48-359 time correcting circuit including manually Operated switches is coupled to an electronic divider circuit [52] L8. Cl.2 58/50 R; 58/85.5; 240/643 which pp the timing Signal to the p y to cop [51] hat. Cl. feet the displayed f i counted thereby h [58] held M Search 58/23 50 time correcting circuit is provided with a safety switch 240/643 which in a first position allows a correction switch to effect correction of a displayed digit and in a second [56] References C'ted position protects against inadvertent time correction UNIT S AT PATENTS and allows the lighting of the light source to make the 3,747,322 7/1973 Eckenrode 523/50 R digital display readable in the darkness. 3,768,247 10/1973 Fujita 58/50 R 3,783,607 1/1974 Feurer 58/50 R 4 Claims 2 Drawmg Flgures OSC/Z LAT/1V6 C/RCU/ T I 2 'POWER SO0E65 C7'A0/V/C V/DER C/IPCU/Z' 5 7 5 9 T l E i J 5 5 t5W/7CAU/VG r c ecu/r 6 L .5

US. Patent Oct. 21, 1975 Sheet 1 of2 3,913,312

056/1 LAT/N6 'POWER SOURCE SWITCH/N6 aecu/r '1 SOLID STATE ELECTRONIC TIMEPIECE' BACKGROUND OF THE INVENTION This invention relates generally to small-sized electronic timepieces having liquid crystal displays and especially to an electronic wristwatch having a light source for lighting the liquid crystal display and a switch for switching the light source so as to render the display visible in the darkness.

Various types of digital displays are known to the prior art. One such digital display is a reflective type wherein time is read by reflecting light from an outside source such as the sun or an electric lamp. When a watch utilizes such reflective display elements, it is impossible to read such display in the dark. Such a disadvantage has been overcome by electronic timepieces utilizing light emitting elements for the digital display thereof. When light emitting elements such as light emitting diodes are utilized, the elements are energized and therefore can be read in the darkness. However, the power consumption of such light emitting elements is excessive. Moreover, since the size of batteries utilized in Wristwatches are extremely limited, the use of such energy consuming display elements shortens the battery life. In order to overcome the excessive drain on the battery, the light emitting diodes remain unlit until such time as the display is switched on in order to be viewed. Thus, an electronic timepiece having a digital display comprised of light emitting elements must be switched on to read the time even when an outside light is available in order to make the digits readable. Accordingly, it is desired to provide an electronic timepiece having a digital display which is readable in the dark but which does not suffer from the above mentioned disadvantages.

SUMMARY OF THE INVENTION Generally speaking, in accordance with the invention, an electronic wristwatch having an oscillator for producing a high frequency time standard signal, an electronic divider circuit for receiving the high frequency time standard signal and providing low frequency timing signals, a liquid crystal digital display for displaying time in response to such low frequency timing signals, is provided with a light source for illuminating the display during darkened conditions. Manually operated correction switches are coupled through a switching circuit to the electronic divider circuit for correcting the time displayed by the digital display. A safety switch is coupled through the switching circuit to the light source. When the safety switch is in a first mode, a manually operated correcting switch is adapted to light the light source to thereby illuminate the liquid crystal display, said safety switch protecting against inadvertent correction of the time displayed. When the time correcting safety switch is in a second mode, the manually operated correction switches operate to correct the digits displayed by the digital display.

Accordingly, it is an object of this invention to provide an improved digital display wristwatch wherein a safety switch protects against the inadvertent correction of the time displayed.

Another object of this invention is to provide an improved digital display electronic timepiece wherein the same switch is used to correct the time displayed and to effect illumination of the digital display.

2 improved electronic wristwatch having a liquid crystal display wherein the minimum energy possible is utilized to read the time displayed in light or dark.

Still another object of this invention is to provide an improved electronic wristwatch having lightreflection or light premeation digital display elements.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction combination of element-s and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawing in which FIG. 1 isa block circuit diagram of an electronic wristwatch in accordance with the instant invention; and

FIG. 2 is a circuit diagram of the switching circuit depicted in FIG. I.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, an electronic timepiece having a conventional liquid crystal digital display 10 comprised of light reflectionor light .permeation type elements for displaying numerals representative of hours, minutes and seconds is depicted. Each digit of the display may, by way of example, take the form of a seven bar display. An oscillating circuit 1, which includes a quartz crystal vibrator, is coupled to an electronic divider circuit 5 for applying high frequency time standard'signals thereto. The electronic divider circuit 5 consists of a multi-stage divider chain capable of counting seconds, minutes and hours and producing, as an output, timing signals representative of present time as reflected by the count in the respective divider stages. The electronic divider circuit would include suitable decoder and driving circuits so that the timing signals are capable of driving display 10. The output of the electronic divider circuit 5 is supplied to digital display 10 for the digital display of time.

A switching circuit 3 consisting of a logic switching circuit particularly illustrated by way of example in FIG. 2, and capable of being actuated by a manually operated switch is coupled to the electronic divider circuit for applying signals thereto and is further coupled to a light source 4 which is disposed proximate to the digital display for illuminating same. Manually operated correction switches 7, 8 and 9 are coupled, at first terminals thereof, to the electronic divider circuit 5 through switching circuit 3, said switches being respectively connected by said switching circuit to the divider stages in the electronic divider circuit 5 which produced the second, minute and hour signals for the separate correction of said divider stages to selectively correct the second, minute or hour time indication displayed by the display l0. The correction may be achieved by indexing the count of the associated divider stages by one upon each operation of the manually operated switches 7, 8 and 9. A safety switch 6 is coupled, at a first terminal, to the second terminals of manually operated switches 7, 8, 9, which other terminal is also connected to power source 2 and is further coupled at both terminals to the switching circuit 3. Power source 2, preferably a battery, is coupled to the oscillating and electronic divider circuits to provide energy therefor.

In operation, the safety switch'6 is used both as a lock for preventing inadvertent operation of the correcting switches and to change over one of the manually operated correction switches 7 to a switch for energizing the light source 4. When the safety switch is opened, and the manually operated switch 7 is actuated, a time correcting signal is applied to the electronic divide r stage corresponding thereto and the associated digit is indexed by 1. On the other hand, when the time correcting safety switch 6 is closed, the manually operated switch 7 is coupled through the switching circuit 3 to the light source 4 and upon actuation thereof illuminates the light source to render the display visible in darkness. Also, when safety switch 6 is closed all of the correction switches are disconnected from the electronic divider circuit so as to remove the possibility of inadvertently changing the digits displayed. Thus, in a small sized electronic timepiece the use of a switch having a dual function saves space'and provides a safety feature in avoiding the correction of a digit by maintaining the safety correction switch 6 in a closed position.

lt will thus be seen that the objects set forth above, among those made'apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of vthe invention which, as a matter of language, might be said to fall therebetween.

What is claimed is:

1. An electronic timepiece having a liquid crystal digital display and comprising oscillator means for generating a relatively high frequency time standard signal; electronic divider means coupled to said oscillator means and adapted to supply low frequency signals to said digital display that are representative of present time in response to said high frequency time standard signal, a light source proximate to the display for illuminating same; safety switch means coupled to said electronic divider circuit and said light source, at least one manually operated correction switch selectively coupled through said safety means to said electronic divider means at a first mode of said safety switch means to effect time correction and being further coupled through said safety switch means to said light source at a second mode of said safety switch means to energize same. J

2. An electronic timepiece having a digital display as claimed in claim 1, wherein said safety switch means includes a switching circuit means and a manually operated safety switch for setting said switching circuit means in said first and second modes. I

3. An electronic timepiece having a digital display as claimed in claim 2, wherein said manually operated safety switch is a two position switch.

4. An electronic timepiece as claimed in claim 2, having at least one further correction switch coupled through said switching circuit means tosaid divider circuit means, each of said first mentioned and further correction switches being adapted to correct different digits of time, said switching circuit means being adapted to operatively couple said further correction switch to said divider circuit means only in said first mode thereof. 

1. An electronic timepiece having a liquid crystal digital display and comprising oscillator means for generating a relatively high frequency time standard signal; electronic divider means coupled to said oscillator means and adapted to supply low frequency signals to said digital display that are representative of present time in response to said high frequency time standard signal, a light source proximate to the display for illuminating same; safety switch means coupled to said electronic divider circuit and said light source, at least one manually operated correction switch selectively coupled through said safety means to said electronic divider means at a first mode of said safety switch means to effect time correction and being further coupled through said safety switch means to said light source at a second mode of said safety switch means to energize same.
 2. An electronic timepiece having a digital display as claimed in claim 1, wherein said safety switch means includes a switching circuit means and a manually operated safety switch for setting said switching circuit means in said first and second modes.
 3. An electronic timepiece having a digital display as claimed in claim 2, wherein said manually operated safety switch is a two position switch.
 4. An electronic timepiece as claimed in claim 2, having at least one further correction switch coupled through said switching circuit means to said divider circuit means, each of said first mentioned and further correction switches being adapted to correct different digits of time, said switching circuit means being adapted to operatively couple said further correction switch to said divider circuit means only in said first mode thereof. 